1. Field of the Invention
The present invention generally relates to a cutting machine for cutting paper into pieces such as documents to be discarded or disposed and, more particularly, to a shredding machine or shredder.
2. Description of the Background Art
A shredder provided with a paper feed mechanism for feeding papers to be cut into pieces is well known and disclosed in, for example, the German Pat. No. 2,214,799 first published on Sept. 27, 1973.
According to the German patent, the paper feed mechanism provided in the shredder comprises a paper tray supported by a machine side wall for movement up and down between lowered and elevated positions, an elastic member such as a spring for urging the paper tray to the elevated position at all times, and a motor-driven paper feed roller positioned immediately above the paper tray in the elevated position. This paper feed mechanism is so designed that, assuming that a batch of papers to be shredded is placed on the paper tray and urged up against the paper feed roller through the paper tray by the action of the spring with the uppermost paper held in contact with the paper feed roller, one or a number of the papers can be fed towards a rotary cutter assembly comprised of a pair of juxtaposed cutting rollers for shredding and discharged into a container after the shredding.
Since according to the German patent the paper tray is normally urged towards the paper feed rollers, the placement of a batch of papers to be shredded on the paper tray requires an operator of the shredder to push the paper tray down towards the lowered position, rendering the machine to require a complicated handling procedure.
Accordingly, the shredding operation is occasionally initiated in a state in which the papers are improperly set on the paper tray. Because of this, some trouble is liable to take place on the papers being fed towards the cutting rollers.
In order to solve this problem, a particular construction has been proposed in which the paper tray is moved by an electric motor. In this construction, however, the motor is subjected to overload when a foreign substance or substances have accidentally obstructed or interrupted the movement of the paper tray. This occasionally causes a breakdown of the shredder and produces some problem during the operation thereof.